1. Field of the Invention
The present invention relates generally to hypodermic syringes and phlebotomy apparatus and more particularly to a safety hypodermic needle for disposable hypodermic syringes and phlebotomy apparatus and a method of using the safety needle to prevent inadvertent needle sticks or punctures.
2. Description of the Prior Art
Infectious diseases can be transmitted to medical personnel and others by way of inadvertent needle sticks or punctures with an infected needle of a hypodermic syringe or phlebotomy apparatus. Cases have been reported in which human HIV (AIDS) infection and other infectious diseases have been transmitted by accidental or inadvertent needle sticks. A number of devices have been developed for the purpose of preventing such needle sticks.
One prior art device comprises a spring-biased tube located within the lumen of the needle. After the needle has been used, the tube is advanced by the spring beyond the needle bevel point thereby protecting medical and other personnel from an inadvertent needle stick. This device is relatively complex, costly and reduces the effective lumen size of the needle.
Another type of prior art device in more common use employs a protective sheath external to the needle which is retractable to permit insertion of the needle into the body of the patient and is then slidable back over the needle past the needle point as, or after, the needle is withdrawn from the body. In some of this type of prior art protective device, a spring or axially resilient sheath is used to extend the sheath over the needle point upon withdrawal of the needle. Several of these prior art devices use a collapsible sheath formed by a plurality of resilient arms surrounding the needle. The arms are bowable or bendable outwardly away from the needle axis to expose the needle and are movable inwardly toward the needle axis with or without a biasing means to again enclose the needle within the sheath. Some of these devices require a positive step or a specific manual act by the phlebotomist or user to deploy the protective sheath after it is withdrawn from the patient's body. Still other devices are made from a plurality of parts making them more complex to manufacture and thus more costly to the consumer.
One of the primary shortcomings of the prior art devices which use protective sheaths of the foregoing type is that during at least some of the period of time between the preparation of the hypodermic syringe for an injection, or the phlebotomy apparatus for entering a vein, and the discarding of the used needle, inadvertent needle sticks of persons other than the patient are still possible. In some prior art devices, the protective sheath does not cover the needle tip prior to administering the needle to the patient, and in others, the protective sheath does not positively prevent exposure of the needle tip after administering the needle to the patient.
It would be desirable, therefore, to provide a safety hypodermic needle for use with a disposable hypodermic syringe, as well as for use with catheter needles and other types of body-penetrating hypodermic needles, that overcomes the foregoing limitations and shortcomings of the prior art devices, has a minimum number of parts, is economical to manufacture and is easy and convenient to use. In particular, it would be highly desirable and advantageous to provide a safety needle that is operable in its “at rest” state to positively prevent inadvertent exposure of the needle point at all times, both before and after use, and to permit exposure of the needle point for use on a patient only in response to a specific manual action or manipulation of the safety needle components on the part of the user, which may include breaking, rupturing or otherwise disengaging a member that retains the safety needle in its “at rest” safe state.
My prior U.S. Pat. No. 5,256,152, the entire disclosure of which is incorporated herein by reference, efficiently and effectively solves many of the aforementioned problems and shortcomings of other prior art safety devices for hypodermic needles and the like. The present invention provides still further improvements in those other prior art safety devices for hypodermic needles as will be described in detail in the following specification.